This is a followup question to (user) micmoo's response on What is the difference between class and instance methods? .
If I change the variable: numberOfPeople from static to a local variable in the class, I get numberOfPeople as 0. I have also added a line to show the numberOfPeople after the variable has been incremented each time. Just to avoid any confusion, my code is as follows:
// Diffrentiating between class method and instance method
#import <Foundation/Foundation.h>
// static int numberOfPeople = 0;
@interface MNPerson : NSObject {
int age; //instance variable
int numberOfPeople;
}
+ (int)population; //class method. Returns how many people have been made.
- (id)init; //instance. Constructs object, increments numberOfPeople by one.
- (int)age; //instance. returns the person age
@end
@implementation MNPerson
int numberOfPeople = 0;
- (id)init{
if (self = [super init]){
numberOfPeople++;
NSLog(@"Number of people = %i", numberOfPeople);
age = 0;
}
return self;
}
+ (int)population{
return numberOfPeople;
}
- (int)age{
return age;
}
@end
int main(int argc, const char *argv[])
{
@autoreleasepool {
MNPerson *micmoo = [[MNPerson alloc] init];
MNPerson *jon = [[MNPerson alloc] init];
NSLog(@"Age: %d",[micmoo age]);
NSLog(@"Number Of people: %d",[MNPerson population]);
}
}
Output:
In init block. Number of people = 1 In init block. Number of people = 1 Age: 0 Number Of people: 0
Case 2: If you change the numberOfPeople in the implementation to 5 (say). The output still does not make sense.
Thank you in advance for your help.
